minimally invasive laminectomy for lumbar spinal stenosis in … · m. alimi et al. 340 j neurosurg...

spine

J Neurosurg Spine Volume 22 • April 2015

cliNical articleJ Neurosurg Spine 22:339–352, 2015

Symptomatic lumbar spinal stenosis (LSS) unrespon-sive to conservative therapy is commonly treated us-ing direct surgical decompression.33 Current guide-

lines recommend additional arthrodesis in patients with LSS and preexisting spondylolisthesis.21,24,31,49,50,52 Various techniques are currently used for direct decompression of LSS. Standard open laminectomy has been shown to be an effective procedure for LSS decompression.36,46,54,60–64,66 However, wide laminectomies violating stabilizing bony and ligamentous structures may exacerbate preexisting spondylolisthesis.19,37 Minimally invasive laminectomy

through tubular or similar retractors is a recently intro-duced alternative procedure for decompression of LSS.47 This technique avoids detachment of the paraspinal mus-cles and may promote preservation of stabilizing ligamen-tous and bony spinal structures.29,30,39,41–45 Biomechanical studies indicate that compared with open laminectomy, minimally invasive laminectomy may result in less post-operative instability.1,6,12,23,34

The current study had two main goals: first, to evalu-ate the efficacy of minimally invasive laminectomy as a decompressive procedure for the treatment of patients with

abbreviatioNS BMI = body mass index; LSS = lumbar spinal stenosis; MCID = minimum clinically important difference; ODI = Oswestry Disability Index; VAS = visual analog scale.accompaNyiNg editorial See pp 337–338. DOI: 10.3171/2014.8.SPINE14687.Submitted June 21, 2013. accepted November 13, 2014. iNclude wheN citiNg Published online January 30, 2015; DOI: 10.3171/2014.11.SPINE13597.diScloSure The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper. Dr. Härtl is a consul-tant for DePuy-Synthes, Lanx, Spine Wave, Brainlab.

Minimally invasive laminectomy for lumbar spinal stenosis in patients with and without preoperative spondylolisthesis: clinical outcome and reoperation ratesmarjan alimi, md, christoph p. hofstetter, md, phd, Se young pyo, md, phd, danika paulo, bS, and roger härtl, md

Weill Cornell Brain and Spine Center, Department of Neurological Surgery, Weill Cornell Medical College, NewYork-Presbyterian Hospital, New York, New York

obJect Surgical decompression is the intervention of choice for lumbar spinal stenosis (LSS) when nonoperative treatment has failed. Standard open laminectomy is an effective procedure, but minimally invasive laminectomy through tubular retractors is an alternative. The aim of this retrospective case series was to evaluate the clinical and radiographic outcomes of this procedure in patients who underwent LSS and to compare outcomes in patients with and without pre-operative spondylolisthesis.methodS Patients with LSS without spondylolisthesis and with stable Grade I spondylolisthesis who had undergone minimally invasive tubular laminectomy between 2004 and 2011 were included in this analysis. Demographic, periopera-tive, and radiographic data were collected. Clinical outcome was evaluated using the Oswestry Disability Index (ODI) and visual analog scale (VAS) scores, as well as Macnab’s criteria.reSultS Among 110 patients, preoperative spondylolisthesis at the level of spinal stenosis was present in 52.5%. At a mean follow-up of 28.8 months, scoring revealed a median improvement of 16% on the ODI, 2.75 on the VAS back, and 3 on the VAS leg, compared with the preoperative baseline (p < 0.0001). The reoperation rate requiring fusion at the same level was 3.5%. Patients with and without preoperative spondylolisthesis had no significant differences in their clinical outcome or reoperation rate.coNcluSioNS Minimally invasive laminectomy is an effective procedure for the treatment of LSS. Reoperation rates for instability are lower than those reported after open laminectomy. Functional improvement is similar in patients with and without preoperative spondylolisthesis. This procedure can be an alternative to open laminectomy. Routine fusion may not be indicated in all patients with LSS and spondylolisthesis.http://thejns.org/doi/abs/10.3171/2014.11.SPINE13597Key wordS lumbar spinal stenosis; spondylolisthesis; minimally invasive laminectomy; tubular retractors; Oswestry Disability Index; visual analog scale; reoperation

339©AANS, 2015

http://thejns.org/doi/abs/10.3171/2014.8.SPINE14687

http://thejns.org/doi/abs/10.3171/2014.8.SPINE14687

m. alimi et al.


LSS. The second aim was to compare the clinical and ra-diographic outcomes of minimally invasive laminectomy in patients with and without preexisting stable spondylo-listhesis.

To better achieve the first goal, outcomes for LSS fol-lowing minimally invasive laminectomies in our retro-spective case series were compared with those achieved via other surgical interventions described in the literature.

methodspatient population

Institutional approval for this study was obtained from Weill Cornell Medical College. Data for this retrospective case series were extracted from the prospectively collect-ed hospital database. We sought all patients who had un-dergone minimally invasive laminectomy for decompres-sion of LSS between 2004 and 2011. Demographic and perioperative data on these patients were collected. For the demographic data, age, sex, body mass index (BMI), smoking status, history of diabetes, and steroid medica-tion use were recorded. Operative and anesthesia reports as well as hospital charts were reviewed to add data on estimated blood loss, number and levels of surgery, com-plications, and length of hospital stay. The presence of preoperative spondylolisthesis was determined on radio-graphic studies. Postoperative radiographs were evaluated to assess changes in the amount and grade of previous spondylolisthesis and/or the development of new slippage. Standardized radiographs were used for assessments, both preoperatively and postoperatively. Patients who had pre-sented with preoperative spondylolisthesis and primarily mechanical back pain and/or instability on flexion/exten-sion films were not included in this study. Comparisons were made between the outcomes of minimally invasive laminectomies in our cohort and the outcomes of other decompressive surgical interventions for LSS, as pub-lished in the literature.

operative procedureWith the patient lying prone under general anesthesia,

a small skin incision is made overlying the target level ap-proximately 1.5 cm lateral to the midline. An 18- or 19-mm tubular retractor is placed over a series of tubular di-lators for retraction, and under the microscope, the inferior edge of the lamina and the inferior edge and base of the spinous process are exposed (Fig. 1). The decompression is performed step by step starting with an ipsilateral par-tial laminectomy using a 3-mm curved matchstick drill bit and bayonet-shaped 2- and 3-mm Kerrison punches (Fig. 2). To achieve appropriate visualization of contralateral structures, the operating table is tilted away from the sur-geon and the tubular retractor is angled medially. Next, the spinous process and the contralateral lamina are undercut using the drill and rongeurs (Fig. 3). The ligamentum fla-

Fig. 1. An 18- or 19-mm tubular retractor is placed over a series of tu-bular dilators for retraction, and under the microscope, the inferior edge of the lamina and the inferior edge and base of the spinous process are exposed. Illustration by Thomas Graves. Copyright Roger Härtl. Pub-lished with permission.

Fig. 2. The decompression is performed starting with an ipsilateral par-tial laminectomy using a 3-mm curved matchstick drill bit and bayonet-shaped 2- and 3-mm Kerrison punches. Illustration by Thomas Graves. Copyright Roger Härtl. Published with permission.

Fig. 3. The operating table is tilted away from the surgeon, and the tubular retractor is angled medially to achieve appropriate visualization of contralateral sublaminar structures. Next, the spinous process and the contralateral lamina are undercut using the drill and rongeurs. The ligamentum flavum is completely exposed cranially until its insertion under the lamina. Illustration by Thomas Graves. Copyright Roger Härtl. Published with permission.

minimally invasive laminectomy for lumbar spinal stenosis

J Neurosurg Spine Volume 22 • April 2015 341

vum is completely exposed bilaterally and cranially until its insertion under the lamina. During the laminectomy, the ligamentum flavum protects the dura. Next, we insert a nerve hook and then a Kerrison rongeur in the midline where the two leaves of the ligamentum flavum meet, an area that is typically identified by the presence of epidural fat (Figs. 4 and 5). These techniques minimize risks of in-jury to the dura. The ligamentum flavum is then removed (Fig. 6). Great care is taken to completely decompress the lateral recess and entirely remove the yellow ligament. This also allows visualization and decompression, if need-ed, of the contralateral exiting and traversing nerve root.

Adequate decompression is always confirmed by iden-tifying certain landmark structures and achieving particu-lar surgical end points, as follows: contralaterally and cau-dally by palpating the pedicle using a ball tip instrument, cranially by confirming complete removal of the yellow ligament and the absence of bony compression of the dura mater, and ipsilaterally by complete removal of the liga-mentum flavum and by clear identification of the lateral aspect of the thecal sac and inspection of the traversing nerve root. As the next and final step, the table and re-tractor are brought back into the initial position, and the ipsilateral decompression is completed.

clinical outcome evaluationThe preoperative and latest available follow-up Os-

westry Disability Index (ODI)14 and visual analog scale (VAS) scores for back, buttock, and leg pain were col-lected and compared. Functional outcome was evaluated using Macnab’s criteria.35 Patients without late follow-up outcome scores recorded in the hospital’s database were contacted by phone, and the ODI and VAS pain scores and Macnab’s level of satisfaction were assessed. These patients were also asked if they had undergone any further lumbar spine surgery at outside medical centers.

A 12-point improvement on the ODI3,20,22 and 3-point improvement on the VAS were regarded as the mini-

mum clinically important difference (MCID).15,16,22 As for functional outcome, 4 levels were defined according to Macnab’s criteria: excellent (no pain; no restriction of activity), good (occasional back or leg pain of sufficient se-verity to interfere with the ability to work), fair (improved functional capacity but handicapped by intermittent pain of sufficient severity to curtail work), or poor (no improve-ment or insufficient improvement to enable increase in ac-tivities; further operative interventions required).35

The patients who required another operation and un-derwent a second surgery at our and other institutions were identified. The indication for the second operation and a description of the procedure were recorded.

radiographic evaluationIn patients with postoperative radiographic studies, the

Fig. 4. A nerve hook is inserted in the midline where the two leaves of the ligamentum flavum meet, an area that is typically identified by the presence of epidural fat. Illustration by Thomas Graves. Copyright Roger Härtl. Published with permission.

Fig. 6. Dural exposure and decompression after complete removal of the ligamentum flavum. The contralateral approach allows visualization and decompression, if needed, of the contralateral exiting and traversing nerve root. Illustration by Thomas Graves. Copyright Roger Härtl. Pub-lished with permission.

Fig. 5. The ligamentum flavum is then carefully removed using Kerrison rongeurs. Illustration by Thomas Graves. Copyright Roger Härtl. Pub-lished with permission.

m. alimi et al.


latest study was used to assess changes in the amount and grade of previous spondylolisthesis and/or development of new slippage.

Statistical analysisPatients with preoperative radiographic studies, who

had been evaluated for the presence or absence of pre-operative spondylolisthesis, were divided into 2 groups: patients with concomitant preoperative spondylolisthesis and those without. We reported results for the entire group of patients as well as for each of the 2 groups separately. Comparisons were made between the 2 different groups and between each group and the entire study group.

Continuous variables are shown as the mean ± stan-dard deviation. Percentages were calculated for categori-cal variables. Differences in categorical variables were as-sessed using the chi-square test. Differences in continuous variables were tested using the independent t-test, and dif-ferences for repeatedly measured variables were assessed using the repeated measures t-test. All analyses were per-formed using appropriate statistical software (SPSS, ver-sion 18.0.0.1, SPSS Inc.). A p value of < 0.05 was consid-ered statistically significant.

resultspatient demographics

One hundred ten consecutive patients, 58 males and 52 females, with isolated LSS who had undergone minimally

invasive laminectomy surgery for decompression were in-cluded in our study. The mean age at surgery was 68.5 years (range 32–89 years; Table 1), and the mean BMI was 28.6 kg/m2. A history positive for smoking, diabetes, and steroid medication use was present in 11.8%, 14.8%, and 4.6% of patients, respectively. In 97 patients with available preoperative imaging, spondylolisthesis Grade I was pres-ent in 51 patients (52.6%), whereas 46 patients (47.4%) did not have preoperative spondylolisthesis.

Surgical detailsOne-, 2-, and 3-level surgeries were done in 57 patients

(51.8%), 47 (42.7%), and 6 (5.4%), respectively. A total of 169 levels were operated on in 110 patients, and the most common level of surgery was L4–5 (50.3% of cases). The L3–4 level made up 29% of cases; L5–S1, 11.2%; and L2–3, the remaining 9.5%. The median estimated blood loss for 1-, 2-, and 3-level surgeries was 25, 50, and 150 ml, respectively (Table 2). More than half of the patients (56%) were discharged on either the day of surgery or the first postoperative day, while the mean duration of hospitaliza-tion was 2.2 ± 2.63 days (range 0–13 days).

clinical outcomeThe mean preoperative ODI was 45.3 ± 19.62 (range

0–88; Tables 3 and 4), which decreased to 28.9 ± 21.76 at a mean follow-up of 28.8 months. An MCID (defined as improvement on the ODI by 12 or more points3,20,22)

table 1. Summary of preoperative characteristics in 110 patients with lSS with and without spondylolisthesis

Characteristic All Patients Patients w/ Spondylolisthesis Patients w/o Spondylolisthesis p Value

No. of patients 110 51 46Mean age at surgery in yrs* 68.5 ± 12.77 72.4 ± 12.69 64.4 ± 12.33 0.002†Sex Male 58 (52.7%) 24 (47.1%) 23 (50%) 0.84 Female 52 (47.3%) 27 (52.9%) 23 (50%)Mean BMI in kg/m²* 28.6 ± 4.74 28.5 ± 4.94 29.2 ± 4.68 0.49Diabetes Yes 14.8% 12.2% 19.6% 0.40 No 85.2% 87.8% 80.4%Smoking Yes 11.8% 9.1% 7.9% 0.84 No 88.2% 90.9% 92.1%Steroid medication use Yes 4.6% 2% 6.5% 0.35 No 95.4% 98% 93.5%Preop spondylolisthesis level‡ L2–3 5 (8.1%) 5 (8.1%) — — L3–4 15 (24.2%) 15 (24.2%) — — L4–5 37 (59.6%) 37 (59.6%) — — L5–S1 5 (8.1%) 5 (8.1%) — —

— = not applicable.* Values expressed as the mean ± standard deviation.† Statistically significant.‡ Fifty-one patients, 62 levels.



was achieved in 54.8% of patients (Table 5). The median preoperative VAS back, buttock, and leg pain scores were 8, 4.5, and 4.6, respectively. At the latest follow-up, the median VAS back, buttock, and leg pain scores decreased to 3.5, 0, and 0, respectively. Three-point improvement on the VAS was regarded as the MCID.15,16,22 The MCID for VAS back, buttock, and leg pain was achieved in 50.0%, 45.2%, and 52.4% of the patients, respectively. All 4 scores indicated statistically significant improvement at the latest follow-up. A comparison of ODI and VAS outcome scores in patients with and without preoperative spondylolisthe-sis showed no significant difference between the 2 groups (Tables 4 and 5).

Functional outcome, as assessed using Macnab’s crite-ria,35 was excellent and good in 71.6% of the patients. A comparison of Macnab’s results in patients with and with-out preoperative spondylolisthesis showed no significant difference (Table 6).

Sixteen cases with dural injuries were not associated with CSF leakage and were intraoperatively repaired us-ing DuraSeal. There were no intraoperative and/or inpa-tient complications. At a mean follow-up of 28 months, the reoperation rate at the same level (with or without sur-gery at a different level) for the entire study group was 12.9%. Among the 11 reoperated patients, 7 (8.2%) un-derwent repeat decompression without fusion at the same level (with or without surgery at a different level), whereas in 3 patients (3.5%) a fusion was performed at the same level. Comparison of total reoperation rates as well as re-operation with fusion in patients with and without preop-erative spondylolisthesis showed no significant difference between the 2 groups (Table 7).

radiographic resultsBecause postoperative imaging was not routinely done

in this retrospective case series, only a limited number of patients (41) had available follow-up imaging. In patients with preoperative spondylolisthesis the mean slippage pri-or to surgery was 5.5 ± 3.04 mm, which increased to 6.4 ± 3.5 at the latest follow-up. This increase did not reach statistical significance. None of the imaged patients with-out preoperative spondylolisthesis demonstrated any slip-page at the latest follow-up. Although we report the radio-graphic follow-up for the study group, we emphasize that radiographic outcome was not used to draw definite con-clusions in this study. Instead, clinical outcome has been mainly used as evidence to draw possible conclusions.

learning curveThe first 55 patients were grouped into an early experi-

ence group and the second 55 cases into a late experience group. Operative time, estimated blood loss, dural injury rates, clinical outcome, Macnab’s criteria, and reoperation rate were compared between these 2 groups. Comparisons showed no statistically significant difference in operative time, estimated blood loss, clinical outcome, and Macnab

table 2. Summary of surgical details in 110 patients who underwent laminectomy

Characteristic All Patients Patients w/ Spondylolisthesis Patients w/o Spondylolisthesis p Value

No. of patients 110 51 46No. of operated levels 169 78 71No. of levels/patient 1 57 (51.8%) 28 (54.9%) 23 (50%) 2 47 (42.7%) 19 (37.3%) 21 (45.7%) 0.60 3 6 (5.5%) 4 (7.8%) 2 (4.3%)Level of surgery L2–3 16 (9.5%) 9 (11.5%) 5 (7%) 0.39 L3–4 49 (29.0%) 19 (24.4%) 23 (32.4%) 0.22 L4–5 85 (50.3%) 42 (53.8%) 36 (50.7%) 0.62 L5–S1 19 (11.2%) 8 (10.3%) 7 (9.9%) 0.94Estimated blood loss (ml)* 1-level op 25 (0;550) 20 (0;150) 50 (0;550) 0.04† 2-level op 50 (0;400) 75 (0;200) 50 (0;400) 0.61 3-level op 150 (100;300) 125 (100;300) 250‡ 0.80Hospital stay (days)* 1 (0;13) 1 (0;12) 1 (0;13) 0.28

* Values expressed as the median (min;max). † Statistically significant.‡ Single case.

table 3. Summary of clinical outcome measures in 84 patients with available preoperative and postoperative data*

Measure Preop Last FU p Value

Mean preop ODI (out of 100)

45.3 ± 19.62 28.9 ± 21.76 <0.0001†

VAS back 8 (0;10) 3.5 (0;10) <0.0001†VAS buttock 4.5 (0;10) 0 (0;10) <0.0001†VAS leg 4.6 (0;10) 0 (0;8) <0.0001†

FU = follow-up.* The mean follow-up duration was 28.8 ± 19.39 months.† Statistically significant.

m. alimi et al.


results in the 2 groups. Dural injuries occurred in 15 cases (27.3%) in the early experience group and in only 1 case (1.8%) in the late experience group (p < 0.0001). Moreover, 9 patients (23.7%) in the early experience group needed reoperation, whereas only 2 patients (4.2%) in the late ex-perience group underwent a second operation (p = 0.008). The follow-up duration for clinical outcome and Macnab’s criteria estimation was 45.7 ± 17.03 months in the early group and 15.5 ± 7.03 months in the late experience group. Similarly, the follow-up duration for reoperation was 44.5 ± 18.34 months in the early group and 15.5 ± 7.03 months in the late experience group. Nonetheless, the period be-tween the first and second operation was found to be simi-lar and not statistically different between the early and late experience groups. The median interval between the first surgery and the reoperation was 16.9 months (minimum 0.2; maximum 39.7).

discussionbackground

Several less-invasive surgical techniques have been in-

troduced for direct decompression of the lumbar spine. The introduction of a less-invasive retractor system dates back to 1991 when Caspar and colleagues proposed the use of less-invasive specular retractors for discectomies.7,17 Independently, Foley and Smith, in 1997, described the tubular microendoscopic discectomy in the lumbar spine, in which endoscopes were used through tubular retrac-tors to perform a discectomy.18 They had worked on this approach in the laboratory since 1994, and the first clini-cal case was performed in early 1996 (K. Foley, personal communication, 2004). The METRx tubular retractor system was introduced in 2003 and permitted the use of the microscope, which allows excellent illumination and visualization of pathology. The use of tubular retractors to access spinal pathology has been associated with sev-eral biomechanical and clinical advantages: First, the ap-proach through a minimally invasive retractor can spare attachments of paraspinal ligaments and muscles, which stabilize the spine. Minimizing injury to paraspinal liga-ments and muscles allows for postoperative strengthening of back muscles and maintains stabilization of the motion

table 4. Summary of clinical improvement in patients with and without spondylolisthesis

Parameter All Patients Patients w/ Spondylolisthesis Patients w/o Spondylolisthesis p Value

No. of patients* 84 37 38FU duration in mos 0.81 Mean ± SD 28.5 ± 19.63 26.7 ± 18.60 27.7 ± 19.43 Median (min;max) 22.8 (6.2;74.3) 20.7 (8.5;74.3) 20.5 (6.2;74.3)% ODI improvement 16.00 (−48.8;62.2) 11.00 (−37.8;62.2) 19.45 (−48.8;53.0) 0.55VAS back improvement (points) 2.75 (−10;10) 3.00 (−6;10) 2.00 (−10;9) 0.26VAS buttock improvement (points) 2.25 (−10;9) 3.50 (−10;8) 2.50 (−5;9) 0.54VAS leg improvement (points) 3.00 (−5;10) 3.00 (−1;9) 3.50 (−5;10) 0.88

* Preoperative and follow-up outcome scores were available in 84 patients; 9 of these patients had no preoperative imaging data.

table 5. Summary of improvements on odi and vaS


Total 84 37 38w/ ODI improvement 59 (70.2%) 24 (64.9%) 26 (68.4%) 0.80w/ MCID in ODI 46 (54.8%) 18 (48.6%) 23 (60.5%) 0.35w/ VAS back pain improvement 56 (66.7%) 25 (67.6%) 24 (63.2%) 0.80w/ MCID in VAS back pain 42 (50.0%) 21 (56.8%) 17 (44.7%) 0.35w/ VAS buttock pain improvement 55 (65.5%) 26 (70.3%) 24 (63.2%) 0.62w/ MCID in VAS buttock pain 38 (45.2%) 19 (51.4%) 17 (44.7%) 0.64w/ VAS leg pain improvement 62 (73.8%) 30 (81.1%) 24 (63.2%) 0.12w/ MCID in VAS leg pain 44 (52.4%) 19 (51.4%) 20 (52.6%) 0.91

table 6. Summary of macnab results

Parameter All Patients Patients w/ Spondylolisthesis Patients w/o Spondylolisthesis p Value of Difference

No. of patients* 74 32 34 Outcome Excellent & good 53 (71.6%) 23 (71.9%) 26 (76.5%) 0.67 Fair & poor 21 (28.4%) 9 (28.1%) 8 (23.5%)

* Data were only available in the listed number of patients.



segment. Second, the minimally invasive approach allows contralateral decompression of the spinal canal, lateral recess, and foramen without another incision while also sparing part of the lamina, spinous process, and interspi-nous ligaments.2,67

The anatomical description and clinical results of a uni-lateral laminotomy for contralateral decompression were first reported by Spetzger in 1997.55,56 Similar observations were also described by McCulloch in 1999.38,59 Adopting tubular retractors for this approach led to excellent de-compression of the contralateral lateral recess and even foraminal disc herniations and contralateral foraminal stenosis.2,67 For example, we reported that synovial cysts can be resected safely and without compromising the facet joint by approaching them from the contralateral side and from “normal” dura and anatomy via tubular retractors.28 Biomechanical and laboratory results indicate that lami-nectomy via tubular retractors or bilateral laminotomies are associated with less destabilization than an open bilat-eral laminectomy.1,5,6,12,23,34,57 In their biomechanical study, Lee et al. demonstrated that bilateral laminotomy was as-sociated with significantly less hypermobility and stiff-ness reduction than a full laminectomy, and they proposed that this could be attributed to preservation of the central posterior osteoligamentous structures in laminotomy.34 In summary, minimally invasive laminectomy via tubular and similar retractors achieves effective neural decom-pression with simultaneous preservation of the stability of motion segments. Figure 7 features a case of LSS in which was achieved complete decompression and a favorable outcome after treatment via this technique.

minimally invasive decompression of lSSMinimally invasive laminectomy through tubular re-

tractors has been shown in previous studies to be a feasible and effective technique for treating LSS.8,30,39,41–45 In the present study we evaluated the outcome of this procedure in a larger group of patients with a longer duration of fol-low-up. The results were compared with those of other de-compressive procedures published in the literature (Table 8). Our study produced results corroborating the findings in previous studies on the same technique. Parikh et al. and Pao et al. reported higher ODI and pain score improve-

ments than we did in the present study;44,45 this may be explained to some extent by the shorter follow-up duration in those studies (9 and 15 months, respectively) compared with ours (28 months).

There is wide variability in the clinical outcome of dif-ferent decompressive procedures in the literature, which makes it difficult to draw definite conclusions (Table 8). Nonetheless, comparisons between the minimally inva-sive laminectomy through tubular retractors and open laminectomy suggest that the former can have clinical out-comes comparable to those for the open procedures, while also having the benefits of minimally invasive surgery.36,46,

54,60–64,66 Moreover, previous studies reporting reopera-tion rates for minimally invasive laminectomy suggest that there is an overall lower reoperation rate associated with this technique compared with that for open laminec-tomy.30,36,39,45,60–63

lumbar Spinal Stenosis and SpondylolisthesisLittle research has been done to compare the outcome

of different decompressive procedures in patients with and without preoperative spondylolisthesis. Clinical re-sults of the current investigation showed no significant difference in outcome for patients with and without pre-operative spondylolisthesis. However, it must be remem-

table 7. reoperation rate


No. of patients* 85 38 38FU duration in mos 0.81 Mean ± SD 28.5 ± 19.63 26.7 ± 18.60 27.7 ± 19.43 Median (min;max) 22.8 (6.2;74.3) 20.7 (8.5;74.3) 20.5 (6.2;74.3)Total reop rate 11 (12.9%) 5 (13.2%) 6 (15.8%) 0.74Isolated decompression of the same (w/ or

w/o different) level(s) 7 (8.2%) 3 (7.8%) 4 (10.5%) 0.55

Fusion w/ or w/o decompression of same (w/ or w/o different) level(s)

3 (3.5%) 2 (5.2%) 1 (2.6%)

Time btwn 1st & 2nd op in mos (min;max) 16.9 (0.2;39.7) 23.1 (6.5;38.1) 10.5 (0.2;39.7) 0.25

* Data were available in the listed number of patients. The type of reoperation procedure performed was unknown in 1 patient.

Fig. 7. Images obtained in a patient with severe LSS at L4–5 treated using minimally invasive laminectomy through tubular retractors. left: Preoperative axial T2-weighted MR image of the lumbar spine at the L4–5 level showing severe stenosis. right: Postoperative MR image at the same level showing marked and effective decompression of the neural elements.

m. alimi et al.


tabl

e 8.

com

paris

on o

f out

com

e am

ong

diffe

rent

dec

ompr

essiv

e pro

cedu

res,

as re

porte

d in

the l

itera

ture

Authors &

Year

Type of Study

No. of C

ases

FU

Duration

ODI

Improvem

ent

(out of 100)

VAS Ba

ck Pain

Improvem

ent

VAS Leg P

ain

Improvem

ent

Satisfac

tion

Total R

eop

Rate

Reop w/

Fusio

n Rate

Open su

rgery

Wilby e

t al., 2006

Prospective co

hort

100

2 yrs

NA76% of pts

improved

87% of pts

improved

NANA

NA

Wein

stein et al., 2007

Random

ized (& observa-

tional) c

ohort

324

2 yrs

24.2

NANA

NA11%

2.6%

Malm

ivaara e

t al., 2007

Random

ized c

linica

l trial

502 y

rs12.8

NANA

NA6%

NA

Wein

stein et al., 200

8Ra

ndom

ized (& observa-

tional) c

ohort

335

2 yrs

20.5

NANA

NA8%

NA

Yaşar et al., 2009

Prospective ca

se se

ries

125

2 yrs

16NA

NANA

NANA

Wein

stein et al., 200

9Ra

ndom

ized (& observa-

tional) c

ohort

264

4 yrs

23NA

NANA

15%

NA

Wein

stein et al., 2010

Random

ized (& observa-

tional) c

ohort

924 y

rs18.7

NANA

NA13%

NA

Pa

rker et al., 2011

Prospective co

hort

542 y

rs18.1

NA4.1

5 poin

tsNA

NANA

Slätis e

t al., 2011

Random

ized c

linica

l trial

472 y

rs13.4

4.2 p

oints

3.7 po

ints

NA2.1

%NA

Less-invasiv

e open s

urgery (open d

ecom

pressio

n w/ le

ss-exte

nsive

remo

val of pst sta

bilizing elem

ents of spine

)

Thom

é et al., 2005

Random

ized c

ohort

40 (in

each of

2 groups)

1 yr

NARe

sidual

pain: 2.3

points (bilat

lamino

t), 3.6

points (unilat

lamino

t)

NAOv

erall

satisfac

tion:

97% (b

ilat

lamino

t),

74% (unilat

lamino

t)

2.5%

(bilat

lamino

t),

5% (unilat

lamino

t)

NA

Yama

shita et al., 2

006

Prospective ob

serva-

tional

705 y

rsNA

2.5 p

oints

4.5 po

ints

NA4.2%

NA

Ca

vuşoğlu

et al., 2

0071

0Prospective

5022

mos

17.1

4.7 po

ints

4.7 po

ints

NA0%

0%

Ca

vuşoğlu

et al., 2

0079

Prospective random

ized

cohort

50 (in

each of

2 groups)

5.4 yrs

17 (unilat

lamino

t)17 (unilat

lamine

c)

NANA

NA2%

(unilat

lamine

c),

0% (unilat

lamino

t)

0% (unilat

lamine

c),

0% (unilat

lamino

t)

Costa

et al., 2

007

Retrospective

374

5 yrs

NA5 p

oints

NANA

0%0%

Orpen e

t al., 2010

Prospective

100

3.5 y

rs32

5 poin

ts6 p

oints

NANA

4% re

quired,

(2% re

fused)

Ho

ng et al., 2

011

Retrospective c

ohort

24 (unilat

lamino

t),

29 (b

ilat

lamino

t)

4 yrs

12.2 (unilat

lamino

t),

15 (b

ilat

lamino

t)

2.3 p

oints (uni-

lat laminot),

4.1 po

ints

(bilat la

minot)

4.7 po

ints (unilat

lamino

t), 5.1

points (bilat

lamino

t)

NANA

0% (unilat

lamino

t),

3.4%

(bilat

lamino

t)

(con

tinue

d)



tabl

e 8.

com

paris

on o

f out

com

e am

ong

diffe

rent

dec

ompr

essiv

e pro

cedu

res,

as re

porte

d in

the l

itera

ture

(con

tinue

d)

Authors &

Year

Type of Study

No. of C

ases

FU

Duration

ODI

Improvem

ent

(out of 100)

VAS Ba

ck Pain

Improvem

ent

VAS Leg P

ain

Improvem

ent

Satisfac

tion

Total R

eop

Rate

Reop w/

Fusio

n Rate

Other M

I procedures (MS

&/or FE)

Ru

etten

et al., 2

009

Random

ized c

linica

l trial

80 (M

S), 81

(FE)

2 yrs

55 (M

S), 56

(FE)

−1.1 points

(MS), 0.4

points (FE

)

7.2 po

ints (MS),

6.7 po

ints

(FE)

NA6.2%

NA

Ca

stro-Menéndez e

t al., 2009

Prospective

50*

4 yrs

30.2

0.84 po

ints

6.02 p

oints

72% ex

cellent

to good

10%

4%

Ko

mp et al., 2

011

Prospective

72†

2 yrs

540.6

points

6.5 p

oints

NA9.5

%NA

MI tubular re

tracto

r laminecto

my

Palmer et al., 2

0024

2Prospective

173 m

osNA

NANA

NANA

NA

Parikh e

t al., 2008

Prospective & retrospec

-tive

609 m

os29.6

4.53 p

oints

5.43 p

oints

NA3.4%

NA

Pa

o et al., 2009

Prospective

5015 mos

47.6

NANA

NANA

NA

Kim et al., 2012

Retrospective o

bserva

-tional cohort

5742 mos

NANA

NANA

15%

7%

Müslüm

an et al., 2

012

Prospective ob

serva-

tional

8424 mos

161.6

3 poin

tsNA

80% ex

cellent

to good

1.2%

0%

Pa

lmer et al., 2

012

Prospective

5427 mos

NA3 p

oints

6 poin

ts80% ov

erall

satisfac

tion

NA2%

Present case

Retrospective

8428 mos

16 (7

0% of pts

improved)

2.75 p

oints

(67%

of pts

improved)

3.0 p

oints

(74% of pts

improved)

72% ex

cellent

to good

12.9%

3.5%

FE = full e

ndoscopy; la

minec =

laminecto

my; la

minot = laminotomy

; MI = minima

lly invasiv

e; MS = microsurgery; N

A = not applicable; ps

t = posterio

r; pts =

patients.

* All patien

ts underwent m

icroendoscopic

decomp

ression

.† All patien

ts underwent full en

doscopic decomp

ression

.

http://www.ncbi.nlm.nih.gov/pubmed?term=%22M%C3%BCsl%C3%BCman AM%22%5BAuthor%5D

m. alimi et al.


bered that our cohort included only patients with “stable” spondylolisthesis, without movement on flexion/extension films, and with neurogenic claudication in the absence of mechanical back pain. The radiographic results corrobo-rated the clinical outcomes. They showed no significant progression of the slippage after surgery in patients with preoperative spondylolisthesis. Similarly, in patients with-out preoperative spondylolisthesis, no slippage developed after surgery. However, we reemphasize that although we have reported on the radiographic presence and extent of slippage in patients with available follow-up imaging, no direct conclusions have been made based on the ra-diographic results per se given the limited availability of these studies. The radiographic findings have been report-ed to provide a more comprehensive picture of the study group and have been discussed and interpreted with cau-tion. On the contrary, in the current study we have mainly focused on clinical outcome and have used it to provide possible evidence and draw careful conclusions. The clini-cal outcome included pain and functional outcome scores, satisfaction level, as well as the reoperation rate. Palmer et al., who studied the feasibility of minimally invasive lami-nectomy via tubular retractors in 2002, also reported no radiographic progression of the slippage at 3 months’ fol-low-up in 8 patients with preoperative slippage.42,43 Given the small sample size and the short follow-up, conclusions for that study were limited. Findings in the current study are consistent with those of Pao et al. and Müslüman et al., who reported no progression of spondylolisthesis fol-lowing a microsurgical unilateral approach for tubular bi-lateral decompression after 2 years’ follow-up.39,44 The re-operation rates in our study compare favorably with those of Kim et al., who reported a 15% total reoperation rate and 7.1% reoperation rate with fusion following bilateral tubular decompressive surgery via a unilateral approach using tubular retractors.30 Those authors concluded that decompression without fusion is more cost-effective than instrumented fusion for a selected group of patients whom they defined as those with leg-dominant pain and stable Grade I spondylolisthesis.

A small number of studies have looked at the outcome in patients with preoperative spondylolisthesis treated us-ing other minimally invasive decompressive techniques such as the full-endoscopic interlaminar approach. These studies all reported very low reoperation rates and/or min-imal progressive spondylolisthesis postoperatively.

Standard open laminectomy, with or without fusion, is currently the most common procedure to treat LSS. However, conventional open laminectomy in the presence of preexisting spondylolisthesis can be associated with a high rate of subsequent instability requiring delayed fu-sion surgery. Radiographic results in Iguchi et al.’s study demonstrated the development of new spondylolisthesis in 6% of the patients without preoperative slippage at 10 years’ follow-up, and the average progression of slippage was 2.3 mm.26 In Epstein’s study, progression from Grade I to Grade II spondylolisthesis at the 2-year follow-up was seen in 31.4% of cases.13 In a well-designed prospective study on open laminectomy in 58 patents with preopera-tive slippage, Blumenthal et al. found that the reoperation rate with fusion was 37.5% at 3 years’ follow-up.4 Current

surgical guidelines state that the “best medical evidence available in the literature confirms the utility of fusion for improving patient outcomes following decompression for stenosis associated with spondylolisthesis.”51

Despite all the variations in outcome among the dif-ferent decompressive procedures, minimally invasive laminectomy through tubular retractors seems to result in clinical outcome and reoperation rates comparable to those for other decompressive procedures.8–11,25,32,36,40,46,53,54,58,60–66 However, the radiographic results suggest that this tech-nique is associated with a lower instability rate than the full-open procedures, probably because of the preserva-tion of posterior elements of the lumbar spine. Results from a cost-utility study showed that tubular retractor–guided decompression without fusion in this setting is more cost-effective than conventional decompression and fusion (Table 9).30

We divided the patients into early and late groups, and no significant differences in operative time, estimated blood loss, and clinical outcome were observed between the two. In contrast, the CSF leakage rate and reoperation rates were higher in the early group. These differences are probably attributable to the learning curve associated with this technique.

Study limitationsFinally, several limitations of the current study should

be noted. It is a retrospective case series based on a pro-spectively collected database. The most important limita-tion lies in the fact that it was not designed to compare the outcome of different decompressive procedures. Thus, we attempted to compare the results of this study with those in the published literature. The wide variety of outcome mea-sures used in these studies complicated the interpretation. In addition, because a number of between-group analyses may have been underpowered given the available sample size, the lack of observed statistical differences between the groups should be interpreted with caution. The cur-rent study provides preliminary estimates of differences between groups that can be used to power larger studies. The p values for between-group comparisons in the range of 0.06–0.20 should be considered as potential evidence for underpowered evaluations, and readers may wish to consider these differences as suggestive of nonsignificant trends. Another limitation of the study lies in the fact that comparison between preoperative and follow-up imaging was possible in only a small group of patients. For a small number of patients, neither pre- nor postoperative imaging was available in the hospital database; therefore, the pres-ence or absence of spondylolisthesis was not determined in this group. Consequently, the small sample size for the radiographic comparison necessitates interpretation with caution.

conclusionsMinimally invasive laminectomy through retractors

is an effective procedure to treat LSS and shows similar results in patients with and without preoperative spondy-lolisthesis with low reoperation rates. This procedure is associated with a lower postoperative instability rate than



tabl

e 9.

com

paris

on o

f out

com

e am

ong

diffe

rent

type

s of d

ecom

pres

sive p

roce

dure

s in

patie

nts w

ith g

rade

i spo

ndylo

listh

esis

Authors &

Year

Type of Study

No. of P

ts w/

GIS*

FU

Duration

(yrs)

ODI

Improvem

ent

(out of 100)

Points

Improvem

ent

on VAS

Back

Points

Improvem

ent

on VAS

Leg

Satisfac

tion

% Pts w/

Spondylolisthesis

Am

ong A

ll Pts

Posto

perative

Progression

of

Spondylolisthesis

Total R

eop

Rate

Reop w/

Fusio

n Rate

Open laminecto

my

Iguchi et al., 200

0Re

trospective

study

10/15

110

JOA improve-

ment:

55.8%

NANA

NA6%

6% ne

w spon

-dylolisthesis

; average

progression

of

slippage: 2.3

mm

NANA

Ep

stein, 20

04No

t specifi

ed35 pts w

/ GIS, 45

w/o a

ny

spondylo-

listhesis

2 NA

NANA

58% to 63%

excellent

to good

surgeon-

base

d outco

me

43%

31.4%

of pts w

/ GIS pro-

gressed to

GIIS

14.2% in pts

w/ GIS,

6.6%

in pts

w/o a

ny

spondylo-

listhesis

8.5%

in pts

w/ GIS,

4.4%

in pts

w/o a

ny

spondylo-

listhesis

Wein

stein et al.,

2009

Random

ized

(& ob

ser-

vational)

cohort

264

4 23

NANA

NA100%

NA15%

NA

Blum

enthal et al.,

2013

Prospective

study

403.6

15NA

NANA

100%

NA37.5%

NA

MI laminecto

my

Podic

hetty et al.,

2006 (m

icrode-

comp

ression

& microendo-

scopic decom

-pressio

n)

Retro

spective

case se

ries

69/220

0.25

NANA

NANA

31%

NANA

1.4%

Iwats

uki et al.,

2007 (m

i-croscopic

decomp

ression

using

Caspar

retra

ctor)

Not specifi

ed7/4

7 2

NANA

NANA

15%

No pr

ogression

NA0%

MI tubular re

tracto

r laminecto

my

Palmer et al.,

2002

43Re

trospective

case se

ries

8/17

0.25

NANA

NANA

47%

No pr

ogression

NANA

Pa

o et al., 2009

Prospective

study

12/60

1.25

47.6

NANA

NA20%

No pr

ogression

NANA

(con

tinue

d)

m. alimi et al.


the conventional open decompressive procedures but has a comparable clinical outcome. Moreover, it has the ben-efits of minimally invasive surgery such as less blood loss and shorter hospital stay. In light of this and other studies demonstrating the potential benefit of tubular and other minimally invasive retractors in decompression surgery, the need for routine fusion surgery in LSS patients with preexisting spondylolisthesis and multilevel LSS should be critically reevaluated.

acknowledgmentsWe acknowledge Dr. Paul Christos for helping in the statistical

analysis of the current study. We also thank AOSpine and Baxter for supporting Marjan Alimi’s fellowship.

references 1. Abumi K, Panjabi MM, Kramer KM, Duranceau J, Oxland

T, Crisco JJ: Biomechanical evaluation of lumbar spinal stability after graded facetectomies. Spine (Phila Pa 1976) 15:1142–1147, 1990

2. Berra LV, Foti D, Ampollini A, Faraca G, Zullo N, Musso C: Contralateral approach for far lateral lumbar disc herniations: a modified technique and outcome analysis of nine patients. Spine (Phila Pa 1976) 35:709–713, 2010

3. Beurskens AJ, de Vet HC, Köke AJ, van der Heijden GJ, Knipschild PG: Measuring the functional status of patients with low back pain. Assessment of the quality of four dis-ease-specific questionnaires. Spine (Phila Pa 1976) 20:1017–1028, 1995

4. Blumenthal C, Curran J, Benzel EC, Potter R, Magge SN, Harrington JF Jr, et al: Radiographic predictors of delayed instability following decompression without fusion for degen-erative Grade I lumbar spondylolisthesis. J Neurosurg Spine 18:340–346, 2013

5. Bresnahan L, Ogden AT, Natarajan RN, Fessler RG: A bio-mechanical evaluation of graded posterior element removal for treatment of lumbar stenosis: comparison of a minimally invasive approach with two standard laminectomy tech-niques. Spine (Phila Pa 1976) 34:17–23, 2009

6. Cardoso MJ, Dmitriev AE, Helgeson M, Lehman RA, Kuklo TR, Rosner MK: Does superior-segment facet violation or laminectomy destabilize the adjacent level in lumbar trans-pedicular fixation? An in vitro human cadaveric assessment. Spine (Phila Pa 1976) 33:2868–2873, 2008

7. Caspar W, Campbell B, Barbier DD, Kretschmmer R, Got-fried Y: The Caspar microsurgical discectomy and compari-son with a conventional standard lumbar disc procedure. Neurosurgery 28:78–87, 1991

8. Castro-Menéndez M, Bravo-Ricoy JA, Casal-Moro R, Hernández-Blanco M, Jorge-Barreiro FJ: Midterm outcome after microendoscopic decompressive laminotomy for lum-bar spinal stenosis: 4-year prospective study. Neurosurgery 65:100–110, 2009

9. Cavuşoğlu H, Kaya RA, Türkmenoglu ON, Tuncer C, Colak I, Aydin Y: Midterm outcome after unilateral approach for bilateral decompression of lumbar spinal stenosis: 5-year prospective study. Eur Spine J 16:2133–2142, 2007

10. Cavuşoğlu H, Türkmenoğlu O, Kaya RA, Tuncer C, Colak I, Sahin Y, et al: Efficacy of unilateral laminectomy for bilater-al decompression in lumbar spinal stenosis. Turk Neurosurg 17:100–108, 2007

11. Costa F, Sassi M, Cardia A, Ortolina A, De Santis A, Luc-carell G, et al: Degenerative lumbar spinal stenosis: analysis of results in a series of 374 patients treated with unilateral laminotomy for bilateral microdecompression. J Neurosurg Spine 7:579–586, 2007ta

ble

9. co

mpa

rison

of o

utco

me a

mon

g di

ffere

nt ty

pes o

f dec

ompr

essiv

e pro

cedu

res i

n pa

tient

s with

gra

de i s

pond

ylolis

thes

is (c

ontin

ued)

Authors &

Year

Type of Study

No. of P

ts w/

GIS*

FU

Duration

(yrs)

ODI

Improvem

ent

(out of 100)

Points

Improvem

ent

on VAS

Back

Points

Improvem

ent

on VAS

Leg

Satisfac

tion

% Pts w/

Spondylolisthesis

Am

ong A

ll Pts

Posto

perative

Progression

of

Spondylolisthesis

Total R

eop

Rate

Reop w/

Fusio

n Rate

MI tubular re

tracto

r laminecto

my (c

ontin

ued)

Müslüm

an et al.,

2012

Prospective

observa-

tional study

25/84

2 16

1.63

NA80% ex

cel-

lent to

good

30%

No pr

ogression

1.2%

0%

Kim et al., 2012

Retro

spective

obser-

vational

cohort

573.5

NANA

NANA

100%

NA15%

7.1%

Present case

Retro

spective

study

51 pts w

/ GIS, 46

w/o a

ny

spondylo-

listhesis

2.4

16 (7

0% of

pts im

-proved)

2.75 (67%

of pts

improved)

3.0 (

74%

of pts

improved)

72% ex

cel-

lent to

good

52%

No pr

ogression

13.2% in pts

w/ GIS,

15.8%

in

pts w/o any

spondylo-

listhesis

5.2%

in pts

w/ GIS,

2.6%

in pts

w/o a

ny

spondylo-

listhesis

GIS = Grade I sp

ondylolisthesis

; JOA

= Ja

panese Orth

opaedic

Association

.* Lis

ted a

lone, per the total num

ber o

f patien

ts in the s

tudy, or a

long w

ith the n

umber o

f patien

ts without any sp

ondylolisthesis

.



12. Delank KS, Gercek E, Kuhn S, Hartmann F, Hely H, Rölling-hoff M, et al: How does spinal canal decompression and dor-sal stabilization affect segmental mobility? A biomechanical study. Arch Orthop Trauma Surg 130:285–292, 2010

13. Epstein NE: Lumbar laminectomy for the resection of syno-vial cysts and coexisting lumbar spinal stenosis or degenera-tive spondylolisthesis: an outcome study. Spine (Phila Pa 1976) 29:1049–1056, 2004

14. Fairbank JC, Couper J, Davies JB, O’Brien JP: The Oswes-try low back pain disability questionnaire. Physiotherapy 66:271–273, 1980

15. Farrar JT, Portenoy RK, Berlin JA, Kinman JL, Strom BL: Defining the clinically important difference in pain outcome measures. Pain 88:287–294, 2000

16. Farrar JT, Young JP Jr, LaMoreaux L, Werth JL, Poole RM: Clinical importance of changes in chronic pain intensity measured on an 11-point numerical pain rating scale. Pain 94:149–158, 2001

17. Faubert C, Caspar W: Lumbar percutaneous discectomy. Initial experience in 28 cases. Neuroradiology 33:407–410, 1991

18. Foley KT, Smith MM: Microendoscopic discectomy. Tech Neurosurg 3:301–307, 1997

19. Fox MW, Onofrio BM, Onofrio BM, Hanssen AD: Clinical outcomes and radiological instability following decompres-sive lumbar laminectomy for degenerative spinal stenosis: a comparison of patients undergoing concomitant arthrodesis versus decompression alone. J Neurosurg 85:793–802, 1996

20. Fritz JM, Irrgang JJ: A comparison of a modified Oswestry Low Back Pain Disability Questionnaire and the Quebec Back Pain Disability Scale. Phys Ther 81:776–788, 2001

21. Glassman SD, Carreon LY, Djurasovic M, Dimar JR, Johnson JR, Puno RM, et al: Lumbar fusion outcomes stratified by specific diagnostic indication. Spine J 9:13–21, 2009

22. Hägg O, Fritzell P, Nordwall A: The clinical importance of changes in outcome scores after treatment for chronic low back pain. Eur Spine J 12:12–20, 2003

23. Hamasaki T, Tanaka N, Kim J, Okada M, Ochi M, Hut-ton WC: Biomechanical assessment of minimally invasive decompression for lumbar spinal canal stenosis: a cadaver study. J Spinal Disord Tech 22:486–491, 2009

24. Herkowitz HN: Degenerative lumbar spondylolisthesis: evo-lution of surgical management. Spine J 9:605–606, 2009

25. Hong SW, Choi KY, Ahn Y, Baek OK, Wang JC, Lee SH, et al: A comparison of unilateral and bilateral laminotomies for decompression of L4-L5 spinal stenosis. Spine (Phila Pa 1976) 36:E172–E178, 2011

26. Iguchi T, Kurihara A, Nakayama J, Sato K, Kurosaka M, Yamasaki K: Minimum 10-year outcome of decompressive laminectomy for degenerative lumbar spinal stenosis. Spine (Phila Pa 1976) 25:1754–1759, 2000

27. Iwatsuki K, Yoshimine T, Aoki M: Bilateral interlaminar fenestration and unroofing for the decompression of nerve roots by using a unilateral approach in lumbar canal stenosis. Surg Neurol 68:487–492, 2007

28. James A, Laufer I, Parikh K, Nagineni VV, Saleh TO, Härtl R: Lumbar juxtafacet cyst resection: the facet sparing con-tralateral minimally invasive surgical approach. J Spinal Disord Tech 25:E13–E17, 2012

29. Khoo LT, Fessler RG: Microendoscopic decompressive lami-notomy for the treatment of lumbar stenosis. Neurosurgery 51 (5 Suppl):S146–S154, 2002

30. Kim S, Mortaz Hedjri S, Coyte PC, Rampersaud YR: Cost-utility of lumbar decompression with or without fusion for patients with symptomatic degenerative lumbar spondylolis-thesis. Spine J 12:44–54, 2012

31. Knaub MA, Won DS, McGuire R, Herkowitz HN: Lumbar spinal stenosis: indications for arthrodesis and spinal instru-mentation. Instr Course Lect 54:313–319, 2005

32. Komp M, Hahn P, Merk H, Godolias G, Ruetten S: Bilateral

operation of lumbar degenerative central spinal stenosis in full-endoscopic interlaminar technique with unilateral ap-proach: prospective 2-year results of 74 patients. J Spinal Disord Tech 24:281–287, 2011

33. Kovacs FM, Urrútia G, Alarcón JD: Surgery versus conser-vative treatment for symptomatic lumbar spinal stenosis: a systematic review of randomized controlled trials. Spine (Phila Pa 1976) 36:E1335–E1351, 2011

34. Lee MJ, Bransford RJ, Bellabarba C, Chapman JR, Cohen AM, Harrington RM, et al: The effect of bilateral lami-notomy versus laminectomy on the motion and stiffness of the human lumbar spine: a biomechanical comparison. Spine (Phila Pa 1976) 35:1789–1793, 2010

35. Macnab I: Negative disc exploration. An analysis of the causes of nerve-root involvement in sixty-eight patients. J Bone Joint Surg Am 53:891–903, 1971

36. Malmivaara A, Slätis P, Heliövaara M, Sainio P, Kinnunen H, Kankare J, et al: Surgical or nonoperative treatment for lumbar spinal stenosis? A randomized controlled trial. Spine (Phila Pa 1976) 32:1–8, 2007

37. Mardjetko SM, Connolly PJ, Shott S: Degenerative lumbar spondylolisthesis. A meta-analysis of literature 1970-1993. Spine (Phila Pa 1976) 19 (20 Suppl):2256S–2265S, 1994

38. McCulloch JA, Young PH: Musculoskeletal and neuroanat-omy of the lumbar spine, in Essentials of Spinal Microsur-gery. Philadelphia: Lippincott-Raven, 1998, pp 249–292

39. Müslüman AM, Cansever T, Yılmaz A, Çavuşoğlu H, Yüce İ, Aydın Y: Midterm outcome after a microsurgical unilateral approach for bilateral decompression of lumbar degenerative spondylolisthesis. J Neurosurg Spine 16:68–76, 2012

40. Orpen NM, Corner JA, Shetty RR, Marshall R: Micro-decompression for lumbar spinal stenosis: the early outcome using a modified surgical technique. J Bone Joint Surg Br 92:550–554, 2010

41. Palmer S, Davison L: Minimally invasive surgical treatment of lumbar spinal stenosis: two-year follow-up in 54 patients. Surg Neurol Int 3:41, 2012

42. Palmer S, Turner R, Palmer R: Bilateral decompression of lumbar spinal stenosis involving a unilateral approach with microscope and tubular retractor system. J Neurosurg 97 (2 Suppl):213–217, 2002

43. Palmer S, Turner R, Palmer R: Bilateral decompressive surgery in lumbar spinal stenosis associated with spondylo-listhesis: unilateral approach and use of a microscope and tubular retractor system. Neurosurg Focus 13(1):E4, 2002

44. Pao JL, Chen WC, Chen PQ: Clinical outcomes of microen-doscopic decompressive laminotomy for degenerative lumbar spinal stenosis. Eur Spine J 18:672–678, 2009

45. Parikh K, Tomasino A, Knopman J, Boockvar J, Härtl R: Operative results and learning curve: microscope-assisted tubular microsurgery for 1- and 2-level discectomies and laminectomies. Neurosurg Focus 25(2):E14, 2008

46. Parker SL, Fulchiero EC, Davis BJ, Adogwa O, Aaronson OS, Cheng JS, et al: Cost-effectiveness of multilevel hemi-laminectomy for lumbar stenosis-associated radiculopathy. Spine J 11:705–711, 2011

47. Perez-Cruet MJ, Foley KT, Isaacs RE, Rice-Wyllie L, Wel-lington R, Smith MM, et al: Microendoscopic lumbar disc-ectomy: technical note. Neurosurgery 51 (5 Suppl):S129–S136, 2002

48. Podichetty VK, Spears J, Isaacs RE, Booher J, Biscup RS: Complications associated with minimally invasive decom-pression for lumbar spinal stenosis. J Spinal Disord Tech 19:161–166, 2006

49. Resnick DK, Choudhri TF, Dailey AT, Groff MW, Khoo L, Matz PG, et al: Guidelines for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 2: assessment of functional outcome. J Neurosurg Spine 2:639–646, 2005

m. alimi et al.


50. Resnick DK, Choudhri TF, Dailey AT, Groff MW, Khoo L, Matz PG, et al: Guidelines for the performance of fusion pro-cedures for degenerative disease of the lumbar spine. Part 7: intractable low-back pain without stenosis or spondylolisthe-sis. J Neurosurg Spine 2:670–672, 2005

51. Resnick DK, Choudhri TF, Dailey AT, Groff MW, Khoo L, Matz PG, et al: Guidelines for the performance of fusion pro-cedures for degenerative disease of the lumbar spine. Part 9: fusion in patients with stenosis and spondylolisthesis. J Neu-rosurg Spine 2:679–685, 2005

52. Resnick DK, Choudhri TF, Dailey AT, Groff MW, Khoo L, Matz PG, et al: Guidelines for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 10: fusion following decompression in patients with stenosis without spondylolisthesis. J Neurosurg Spine 2:686–691, 2005

53. Ruetten S, Komp M, Merk H, Godolias G: Surgical treatment for lumbar lateral recess stenosis with the full-endoscopic interlaminar approach versus conventional microsurgical technique: a prospective, randomized, controlled study. J Neurosurg Spine 10:476–485, 2009

54. Slätis P, Malmivaara A, Heliövaara M, Sainio P, Herno A, Kankare J, et al: Long-term results of surgery for lumbar spinal stenosis: a randomised controlled trial. Eur Spine J 20:1174–1181, 2011

55. Spetzger U, Bertalanffy H, Naujokat C, von Keyserlingk DG, Gilsbach JM: Unilateral laminotomy for bilateral decompres-sion of lumbar spinal stenosis. Part I: Anatomical and surgi-cal considerations. Acta Neurochir (Wien) 139:392–396, 1997

56. Spetzger U, Bertalanffy H, Reinges MH, Gilsbach JM: Uni-lateral laminotomy for bilateral decompression of lumbar spinal stenosis. Part II: Clinical experiences. Acta Neurochir (Wien) 139:397–403, 1997

57. Tai CL, Hsieh PH, Chen WP, Chen LH, Chen WJ, Lai PL: Biomechanical comparison of lumbar spine instability be-tween laminectomy and bilateral laminotomy for spinal stenosis syndrome – an experimental study in porcine model. BMC Musculoskelet Disord 9:84, 2008

58. Thomé C, Zevgaridis D, Leheta O, Bäzner H, Pöckler-Schö-niger C, Wöhrle J, et al: Outcome after less-invasive decom-pression of lumbar spinal stenosis: a randomized comparison of unilateral laminotomy, bilateral laminotomy, and laminec-tomy. J Neurosurg Spine 3:129–141, 2005

59. Weiner BK, Walker M, Brower RS, McCulloch JA: Microde-compression for lumbar spinal canal stenosis. Spine (Phila Pa 1976) 24:2268–2272, 1999

60. Weinstein JN, Lurie JD, Tosteson TD, Hanscom B, Tosteson AN, Blood EA, et al: Surgical versus nonsurgical treatment for lumbar degenerative spondylolisthesis. N Engl J Med 356:2257–2270, 2007

61. Weinstein JN, Lurie JD, Tosteson TD, Zhao W, Blood EA, Tosteson AN, et al: Surgical compared with nonoperative

treatment for lumbar degenerative spondylolisthesis. Four-year results in the Spine Patient Outcomes Research Trial (SPORT) randomized and observational cohorts. J Bone Joint Surg Am 91:1295–1304, 2009

62. Weinstein JN, Tosteson TD, Lurie JD, Tosteson A, Blood E, Herkowitz H, et al: Surgical versus nonoperative treat-ment for lumbar spinal stenosis four-year results of the Spine Patient Outcomes Research Trial. Spine (Phila Pa 1976) 35:1329–1338, 2010

63. Weinstein JN, Tosteson TD, Lurie JD, Tosteson AN, Blood E, Hanscom B, et al: Surgical versus nonsurgical therapy for lumbar spinal stenosis. N Engl J Med 358:794–810, 2008

64. Wilby MJ, Seeley H, Laing RJ: Laminectomy for lumbar ca-nal stenosis: a safe and effective treatment. Br J Neurosurg 20:391–395, 2006

65. Yamashita K, Ohzono K, Hiroshima K: Five-year outcomes of surgical treatment for degenerative lumbar spinal steno-sis: a prospective observational study of symptom severity at standard intervals after surgery. Spine (Phila Pa 1976) 31:1484–1490, 2006

66. Yaşar B, Simşek S, Er U, Yiğitkanli K, Ekşioğlu E, Altuğ T, et al: Functional and clinical evaluation for the surgical treat-ment of degenerative stenosis of the lumbar spinal canal. J Neurosurg Spine 11:347–352, 2009

67. Yeom JS, Kim KH, Hong SW, Park KW, Chang BS, Lee CK, et al: A minimally invasive technique for L5-S1 intra-foraminal disc herniations: microdiscectomy with a tubular retractor via a contralateral approach. J Neurosurg Spine 8:193–198, 2008

author contributionsConception and design: Härtl, Alimi, Hofstetter, Pyo. Acquisition of data: Alimi, Paulo. Analysis and interpretation of data: Härtl, Alimi, Hofstetter. Drafting the article: Alimi. Critically revising the article: all authors. Reviewed submitted version of manu-script: all authors. Statistical analysis: Alimi, Hofstetter. Study supervision: Härtl.

Supplemental informationPrevious PresentationPortions of this work were presented in abstract/poster form at the 29th Annual Meeting of the AANS/CNS Section on Disorders of the Spine and Peripheral Nerves held in Phoenix, Arizona, on March 6–9, 2013.

correspondenceRoger Härtl, MD, Department of Neurological Surgery, Weill Cornell Brain and Spine Institute, 525 E. 68th St., Box 99, New York, NY 10065. email: [email protected].

minimally invasive laminectomy for lumbar spinal stenosis in … · m. alimi et al. 340 j neurosurg...

Documents